#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>

using namespace std;

const int N = 2010, M = 10010;

int n, m;
int h[N], w[M], e[M], ne[M], idx;
int dist[N], cnt[N];
bool st[N];

void add(int a, int b, int c) {
	e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx ++ ;
}

bool spfa() {
	queue<int> q;
	
	for (int i = 1; i <= n; i ++ ) {
		st[i] = true;
		q.push(i); 
	}
	
	while (q.size() ) {
		int t = q.front() ;
		q.pop() ;
		
		st[t] = false;
		
		for (int i = h[t]; i != -1; i = ne[i]) {
			int j = e[i];
			if (dist[j] > dist[t] + w[i]) {
				dist[j] = dist[t] + w[i];
				cnt[j] = cnt[t] + 1;
				
				if (cnt[j] >= n) return true;
				if (!st[j]) {
					q.push(j);
					st[j] = true; 
				}
			}
		}
	}
	
	return false;
}

int main() {
	scanf("%d%d", &n, &m);
	
	memset(h, -1, sizeof h);
	
	while (m -- ) {
		int a, b, c;
		scanf("%d%d%d", &a, &b, &c);
		add(a, b, c);
	}
	
	if (spfa()) puts("Yes");
	else puts("No");
	
	return 0;
}